Recordable data storage medium including property data

ABSTRACT

In a recordable data storage medium on which property data was recorded after having been modulated and on which data that is decodable by a cryptographic key to be generated from the property data was recorded, the property data was preferably modulated by a different method from that applied to a read-only data storage medium. Then, an optical disc drive, having no ability to distinguish the recordable data storage medium from the read-only data storage medium, cannot read the recordable data storage medium. Consequently, a greater number of drives should be equipped with the function of recognizing the type of a given data storage medium and the copyright protection function should be consolidated.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Section 371 of PCT/JP01/04141, filed May 17, 2001,published in the Japanese language on Nov. 22, 2001 under WO 01/88917,the disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a data storage medium such as anoptical disc, which can be used effectively to guarantee appropriatecopyright protection, and a read drive for use to read the medium.

BACKGROUND ART

Disk storage media, on which various types of data (or information) canbe stored, include read-only data storage media and recordable datastorage media.

Generally speaking, in the past, read-only drives for reading data thatwas written on read-only data storage media were popularized first, andthen optical disc drives for writing data on recordable data storagemedia or reading the data that was written on recordable data storagemedia were popularized. Accordingly, to make the recordable data storagemedia also readable by the read-only drives, the physical dimensions(including the diameter and thickness of discs), physical properties(such as reflectance) and data recording format of the recordable datastorage media were matched with those of the read-only data storagemedia as closely as possible. As a result, however, even copyrighteddata, recorded on a read-only data storage medium, may be easily copiedonto a recordable data storage medium. Thus, the copyright of such datahas often been infringed.

To avoid this unwanted situation, various techniques of discouragingillegal duplication have been developed and used in the field of opticaldiscs. Hereinafter, a conventional technique of discouraging suchillegal duplication will be described with reference to FIGS. 1 through3.

First, a conventional recordable data storage medium will be describedwith reference to FIG. 1. Modulated property data 15 is recorded on arecordable data storage medium 1 during the manufacturing processthereof before the storage medium 1 is put on the market. The modulatedproperty data 15 is obtained by getting property data 4 (i.e.,information unique to each storage medium) modulated by a modulatingsection 16. The property data 4 may be a disc ID, for example.

A user who bought the recordable data storage medium 1 can write thedata 6 (to be stored in the removable storage medium) on the user areaof the recordable data storage medium 1 or read the data 6 from the userarea by using an optical disc drive.

Such an apparatus that can write the data on the recordable data storagemedium 1 and/or read the data from the medium 1 (i.e., the optical discdrive) includes a demodulating section 17 for demodulating the modulatedproperty data 15 that was recorded on the recordable data storage medium1 and a decrypting section 10 for decrypting encrypted data 2 that hasalso been written on the recordable data storage medium 1.

Where the user writes the encrypted data 2 on the recordable datastorage medium 1, the data 6 is converted into the encrypted data 2(e.g., scrambled data) by an encrypting section 7 inside the opticaldisc drive and then written on the recordable data storage medium 1. Themodulated property data 15 that has been recorded in advance on therecordable data storage medium 1 is used for this encryption. Morespecifically, before the data 6 is encrypted, the modulated propertydata 15 is read out from the recordable data storage medium 1 and thendemodulated by the demodulating section 17. Thereafter, the encrypteddata 2 is generated from the data 6 by using the demodulated propertydata 15.

In reading the data from the recordable data storage medium 1, first,the modulated property data 15 is read and then demodulated into theproperty data 4 by the demodulating section 17. Next, the encrypted data2 is read from the user data area on the recordable data storage medium1 and then transmitted to the decrypting section 10, where the encrypteddata 2 is decrypted by using the demodulated property data 4.

Next, a read-only data storage medium will be described with referenceto FIG. 2.

After encrypted data 2, modulated property data 15 and recordedencryption data 12 have been recorded on a read-only data storage medium14 during the manufacturing process thereof, the read-only data storagemedium 14 is shipped. The modulated property data 15 is obtained bygetting the property data 4 (i.e., information unique to each storagemedium) modulated by the modulating section 16.

The encrypted data 2 is generated by encrypting the data 6 with acryptographic key. This cryptographic key is generated by usingencryption data 11. The data 6 to be copyrighted is encrypted with thecryptographic key into the encrypted data 2, which is then recorded onthe read-only storage medium 2.

The encrypted data 2 and the recorded encryption data 12 are recorded ondifferent areas on the storage medium during the manufacturing processthereof. The modulated property data 15 may not be recorded on theread-only data storage medium 14. In a DVD-ROM, for example, therecorded encryption data 12 includes cryptographic key information foruse in a contents scrambling system (CSS), and the encrypted data 12 isobtained by scrambling the contents of the data 6 in accordance with theinformation.

A user who bought the read-only data storage medium 14 can decode theencrypted data 2 by using a regular read drive. The read drive forreading such a read-only data storage medium 14 includes: a demodulatingsection 17 for demodulating the modulated property data 15 that wasrecorded on the read-only data storage medium 14; a decrypting section10 for decrypting the encrypted data 2 that was recorded on therecordable data storage medium 1; a type recognizing section 8 fordetermining whether the storage medium to read is a read-only datastorage medium or a recordable data storage medium; and a switch 13 forprohibiting or allowing the use of the recorded encryption data 12 inaccordance with the result obtained by the type recognizing section 8.

FIGS. 3( a) through 3(c) are schematic representations showing aphysical difference between the read-only data storage medium and therecordable data storage medium. Specifically, FIG. 3( a) illustratestracks of the read-only data storage medium, FIG. 3( b) illustratesrecording tracks of the recordable data storage medium, and FIG. 3( c)illustrates a broader area including the portion shown in FIG. 3( b).

On the read-only data storage medium, pits 51 are formed on the datarecording tracks 50 as shown in FIG. 3( a). On the recordable datastorage medium on the other hand, recording marks 53 are formed ongrooves 52 functioning as data recording tracks as shown in FIG. 3( b).As used herein, the “recording marks” 53 are portions of a recordingfilm, of which the properties (e.g., reflectance) have been changedthrough the exposure to a laser beam.

On a recordable data storage medium such as a DVD-R or a DVD-RW, pits 54are formed on a land portion between the grooves 52 and the grooves 52slightly wind in a regular period and within a predetermined amplitudeas shown in FIG. 3( c). Such winding of the grooves 52 is called“wobbling”. No track wobbling like this is observed on any read-onlydata storage medium.

By detecting the groove wobbling such as that shown in FIG. 3( c), thetype recognizing section 8 of the read drive can determine whether thestorage medium to read is a read-only data storage medium or arecordable data storage medium. A detector that may be used as such atype recognizing section 8 is disclosed in U.S. Pat. Nos. 5,459,706 and6,088,307, which are hereby incorporated by reference.

As shown in FIG. 2, the encrypted data 2, which has been read out fromthe read-only data storage medium 14, is decrypted by the decryptingsection 10 using the recorded encryption data 12. In this case, the typerecognizing section 8 senses that the data storage medium being read isa read-only data storage medium and turns the switch 13 ON. Ifnecessary, the modulated property data 15 is demodulated by thedemodulating section 17 and used.

Next, it will be described what if one tries to read the recordable datastorage medium 1, onto which the encrypted data 2 and the recordedencryption data 12 were illegally copied as they are from the read-onlydata storage medium 14, by using the read drive.

In that case, the type recognizing section 8 senses that the storagemedium to read is not a read-only data storage medium and turns theswitch 13 OFF. As a result, the recorded encryption data 12 is notsupplied to the decrypting section 10 and the encrypted data 2 is notdecoded.

However, not every read drive includes the type recognizing section 8. Aread drive with no type recognizing section 8 cannot distinguishrecordable data storage media 1 from read-only data storage media 14 andcannot stop the decrypting section 10 from performing its decryptingoperation. As a result, such a read drive reads even the data that wascopied illegally onto a recordable data storage medium 1.

As is clear from the foregoing description, a read drive with no abilityto distinguish recordable data storage media from read-only data storagemedia reads the encrypted data not just from a read-only data storagemedium or a recordable data storage medium, on which the data waswritten legally, but also from a recordable data storage medium ontowhich the encrypted data was illegally copied from a read-only datastorage medium.

In the field of optical discs, examples of known read-only data storagemedia include CD-ROMs and DVD-ROMs while examples of known recordabledata storage media include CD-Rs, CD-RWs, DVD-Rs, DVD-RWs and DVD-RAMs.

This illegal duplication problem happens not only in optical discs butalso in any other type of data storage media that are formatted suchthat read-only and recordable versions thereof are both readable by thesame read drive.

In order to overcome the problems described above, an object of thepresent invention is to provide a recordable data storage medium, fromwhich not a read drive with no ability to distinguish recordable andread-only data storage media but just a read drive that guaranteesappropriate copyright protection can read user data that was encryptedwith property data.

Another object of the present invention is to provide a read drive thatprohibits the decrypting section from decoding encrypted data that wasillegally copied onto a recordable data storage medium but that allowsit to decode legally copied encrypted data.

DISCLOSURE OF INVENTION

A recordable data storage medium according to the present inventionincludes an area on which property data, unique to the recordable datastorage medium, was recorded and on which user data to be used by a userwill be written after having been encrypted with the property data. Theuser data will be written on the area in the same format as a first dataformat for a read-only data storage medium. On the read-only datastorage medium, user data to be used by the user was written in thefirst data format and property data, unique to the read-only datastorage medium, was recorded in a second data format. At least portionof the property data was recorded on the recordable data storage mediumin a third data format that is different from the second data format.

In a preferred embodiment, the at least portion of the property datathat was recorded in the third data format includes cryptographic keyinformation for use to encrypt the user data.

In another preferred embodiment, the third data format uses a differentmodulation method from that of the second data format.

In another preferred embodiment, the modulation method for the thirddata format satisfies an inverted polarity relationship with respect tothe modulation method for the second data format.

In another preferred embodiment, the modulation method for the seconddata format is a method of converting data “0” into channel data “10”and data “1” into channel data “01”, respectively, and the modulationmethod for the third data format is a method of converting data “0” intochannel data “01” and data “1” into channel data “10”, respectively.

In another preferred embodiment, the third data format uses a differenterror correction data format from that of the second data format.

In another preferred embodiment, the error correction data format of thethird data format uses a different generator polynomial from that of theerror correction data format of the second data format.

In another preferred embodiment, at least portion of the property datawas recorded on a burst cutting area (BCA).

An optical disc drive according to the present invention can read userdata from a recordable data storage medium, on which property data,unique to the recordable data storage medium, was recorded and on whichthe user data to be used by a user is writable. The optical disc driveincludes: a type recognizing section for distinguishing the recordabledata storage medium from a read-only data storage medium; and propertydata reading means for selecting one of multiple methods of reading theproperty data in accordance with a result obtained by the typerecognizing section.

In a preferred embodiment, the read-only data storage medium hasrecorded thereon user data to be used by the user and property data,unique to the read-only data storage medium, in first and second dataformats, respectively. The user data will be written on the recordabledata storage medium in the same first data format as that of theread-only data storage medium and at least portion of the property datawas recorded on the recordable data storage medium in a third dataformat, which is different from the second data format.

In another preferred embodiment, the optical disc drive uses a readingmethod compatible with the second data format in reading the propertydata of the read-only data storage medium and uses a reading methodcompatible with the third data format in reading the property data ofthe recordable data storage medium.

In another preferred embodiment, if encrypted user data was written onthe recordable data storage medium, the optical disc drive decodes theuser data in accordance with the information contained in the propertydata that was recorded on the recordable data storage medium.

The type recognizing section distinguishes the read-only data storagemedium from the recordable data storage medium by detecting a physicalfeature of a given data storage medium.

The physical feature is wobbling of recording tracks.

The physical feature is pits that were formed on land portions betweenrecording grooves.

The user data is decodable with a cryptographic key that has beengenerated from the property data.

The third data format uses a different modulation method from that ofthe second data format.

The modulation method for the third data format satisfies an invertedpolarity relationship with respect to the modulation method for thesecond data format.

In reading the property data of the read-only storage medium, theproperty data reading means demodulates channel data “10” into data “0”and channel data “01” into data “1”, respectively. On the other hand, inreading the property data of the recordable storage medium, the propertydata reading means demodulates channel data “01” into data “0” andchannel data “10” into data “1”, respectively.

The third data format uses a different error correction data format fromthat of the second data format.

The error correction data format of the third data format uses adifferent generator polynomial from that of the error correction dataformat of the second data format.

The optical disc drive further includes means for encrypting the userdata in accordance with the information contained in the property data.The optical disc drive writes the encrypted user data on the recordabledata storage medium.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating the flow of signals in aconventional recordable data storage medium during the manufacturing andplayback stages thereof.

FIG. 2 is a block diagram illustrating the flow of signals in aread-only data storage medium during the manufacturing and playbackstages thereof.

FIGS. 3( a) through 3(c) illustrate the physical features of user dataareas in a read-only data storage medium and a recordable data storagemedium.

FIG. 4 illustrates a portion of a read-only data storage medium(DVD-ROM) and a portion of a recordable data storage medium (DVD-R orDVD-RW).

FIG. 5 is a perspective view illustrating a portion of a BCA that may beused to record property data on a data storage medium.

FIG. 6 is a block diagram illustrating the flow of signals in arecordable data storage medium according to the present invention duringthe manufacturing, recording and playback stages thereof.

FIG. 7( a) shows how property data is modulated in a recordable datastorage medium according to the present invention and FIG. 7( b) showshow property data is modulated in a read-only data storage medium, whichis compatible with the recordable data storage medium of the presentinvention.

FIG. 8 is a block diagram illustrating the flow of signals while aread-only data storage medium, which is compatible with the recordabledata storage medium of the present invention, is read by a read driveaccording to the present invention.

FIG. 9 shows how a write operation is performed on a DVD-R disc, whichis used as a recordable data storage medium according to the presentinvention.

FIG. 10 shows how a read operation is performed on the DVD-R disc thatis used as the recordable data storage medium of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will bedescribed with reference to the accompanying drawings.

On a recordable data storage medium according to the present invention,property data, unique to the storage medium, is recorded after havingbeen modulated during the manufacturing process thereof. The propertydata (or the modulated property data) is recorded on a different areafrom the area on which the user, who bought the storage medium, willwrite his or her data. As for a disklike data storage medium such asthat shown in FIG. 4, for example, a “property data recording area” maybe defined within a lead-in area that is located inside (i.e., closer tothe center of the disc than) the “user data recording area”.

The property data may be written in any of various fashions on theproperty data recording area. On a recordable data storage mediumcomplying with the DVD-R standard, for example, the property data may bewritten there by forming slits, extending in the disc radial direction,in the reflective film of the storage medium. These slits may be formedby burning off predetermined portions of the reflective film by a lasertrimming technique, for example. For that reason, the property datarecording area is called a “BCA (burst cutting area)”. Those slitsextend in the disc radial direction and are arranged in a disctangential direction.

FIG. 5 is a partial perspective view illustrating the surface of astorage medium on which a slit 52 was formed in the reflective film 52thereof. A portion of the reflective film 52 including the slit 54 andanother portion of the reflective film 52 including no slits 54 showdifferent reflectances against an incident laser beam. An optical discdrive such as a read-only drive or a read/write drive can read theproperty data by focusing a laser beam on the property data recordingarea of a given storage medium and detecting a variation in theintensity of the reflected light. A method and apparatus of recording adisc ID and other types of property data on a BCA area is described, forexample, in U.S. Pat. No. 6,160,888, which is hereby incorporated byreference.

In a DVD-R, an organic dye recording film is sandwiched between a discsubstrate including guide grooves for tracking thereon and a reflectivefilm. User data is recorded on the recording film by forming marks inthe recording film with a laser beam that has been focused onto therecording film. In a DVD-RW on the other hand, the recording filmthereof is made of a phase-change type recording material.

The user cannot change the property data, which was recorded on arecordable data storage medium, by using a normal optical disc drive.The property data includes information that is uniquely given to eachstorage medium, e.g., a disc ID. When the user encrypts user data andwrites the encrypted user data on the user data recording area, theproperty data may be used as a cryptographic key, for example. Thisproperty data may also be used to decode the encrypted user data. Theuser data may be written in the same data format on both a read-onlydata storage medium and a recordable data storage medium, to which thepresent invention is applicable.

Next, FIG. 6 will be referred to. A recordable data storage medium 1according to this embodiment is shipped after modulated property data 3was recorded thereon during the manufacturing process thereof as shownin FIG. 6. The modulated property data 3 is obtained by getting propertydata 4 modulated by a modulating section 5 such as an RZ modulator. Inthis embodiment, the property data 4 is modulated by a modulation methodB, which is different from the conventional one. The conventionalmodulation method A is the same as the modulation method that is adoptedin recording modulated property data on a read-only data storage medium.In contrast, according to this embodiment, the property data 4 ismodulated by the modulation method B that is different from themodulation method A, which is one of the principal features of thepresent invention.

Hereinafter, the difference between the modulation methods A and B willbe described with reference to FIGS. 7( a) and 7(b).

FIG. 7( a) shows an example in which the property data is recorded bythe modulation method A, while FIG. 7( b) shows an example in which theproperty data is recorded by the modulation method B. In FIGS. 7( a) and7(b), the property data is shown as DATA, which is defined as anarrangement of zeros and ones.

Before recorded on a storage medium, the property data is converted intochannel data by a phase encoding (PE) modulation technique. In themodulation method A, data “0” is converted into channel data “10” anddata “1” is converted into channel data “01”. In the modulation method Bon the other hand, data “0” is converted into channel data “01” and data“1” is converted into channel data “10”. A pair of modulation methodsthat satisfies such a relationship will be herein referred to as“modulation methods satisfying an inverted polarity relationship”.

As can be seen, even if original property data contains the sameinformation, the PE-modulated property data may be defined by one of twodifferent strings of channel bits depending on whether the property datais modulated by the modulation method A or the modulation method B. Inother words, the data format of the property data recorded on theread-only data storage medium is different from that of the propertydata recorded on the recordable data storage medium. These channel bitstrings are recorded on the storage media by an RZ method.

In FIGS. 7( a) and 7(b), the waveform identified by “BCA” represents theproperty data that has been modulated by a PE-RZ modulating section. Inaccordance with this waveform, slit-like openings are formed on portionsof the reflective film that are located in the BCA area of the storagemedium (see FIGS. 4 and 5). More specifically, a laser trimming processmay be carried out such that the Low level portions of the waveform,representing the modulated property data BCA, correspond to the slits 54of the reflective film 52 shown in FIG. 5.

In the illustrated examples, the channel bit data is recorded by the RZmethod, and the widths of the respective slits formed are constant,typically about 10 μm. It should be noted that any information otherthan the property data may be included there.

According to the present invention, even when the original property datais the same, the modulated version of the property data has its dataformat changed depending on whether the property data is subjected tothe modulation method A or the modulation method B. Thus, a portion ofthe storage medium where the modulated property data has been recorded(i.e., a portion of the reflective film that is located in the BCA area)may have one of two different physical shapes (or two different slitarrangement patterns). Accordingly, even if the modulated property datathat was recorded on the BCA area of a read-only data storage medium wascopied onto the BCA area of a recordable data storage medium, thecontents of the original property data could not be demodulated from themodulated property data by any method other than a demodulation methodA.

It should be noted that not all of the property data to be recorded onthe recordable data storage medium has to be modulated by the modulationmethod B. Rather at least portion of the property data to be recordedthere needs to be modulated by a different modulation method.

Next, a read drive for reading the data that was written on therecordable data storage medium of the present invention will bedescribed.

This read drive includes: a type recognizing section 8 for recognizingthe type of a given storage medium to read as a read-only data storagemedium or a recordable data storage medium; and a demodulating section 9for demodulating the modulated property data 3 by selecting either thedemodulation method A or the demodulation method B in accordance withthe result obtained by the type recognizing section 8. In the otherrespects, this read drive may have the same configuration as theconventional read drive or read/write drive.

A read/write drive for writing user data on the recordable data storagemedium of the present invention includes not only various units, eachhaving the same function as the counterpart of the read drive, but alsoother known units for use to write the data.

Next, it will be described how to write encrypted data on a recordabledata storage medium by using the read/write drive.

FIG. 6 will be referred to again. First, the modulated property data 3is demodulated by the demodulating section 9, the output of which issent to an encrypting section 7. In this case, since the medium typerecognizing section 8 has sensed that the storage medium that has beeninserted into the read/write drive is a recordable data storage medium,the demodulation method B is used in the demodulating section 9. Theproperty data that has been demodulated by the demodulating section 9 isused to get the data 6 encrypted, and converted into the encrypted data2, by the encrypting section 6.

Next, it will be described with reference to FIG. 6 again how to readthe encrypted data from the recordable data storage medium 2 by usingthe read drive or read/write drive of the present invention. In thiscase, in accordance with the result obtained by the type recognizingsection 8, the demodulation method B is also selected for use in thedemodulating section 9. As a result, the modulated property data 3 isdemodulated by the demodulating section 9 appropriately. Then, theproperty data 4 demodulated is supplied to the decrypting section 10 andused to decrypt the encrypted data 2.

Next, it will be described what if one tries to read the recordable datastorage medium of this preferred embodiment by using a conventional readdrive having no ability to recognize the type of the given storagemedium to read (or whether it is a recordable data storage medium ornot). In that case, the demodulating section can adopt only thedemodulation method A. Accordingly, the demodulating section cannotappropriately demodulate the modulated property data 3 that wasmodulated by the modulation method B, and cannot decode the encrypteddata 2. Thus, to read the recordable data storage medium of the presentinvention, the read drive must be able to determine whether the givendata storage medium is a read-only data storage medium or a recordabledata storage medium. Then, a greater number of read drives should beequipped with the function of recognizing the type of a given datastorage medium and the copyright protection should be consolidated.

Next, it will be described with reference to FIG. 8 how to read theread-only data storage medium 14 with the read drive of the presentinvention.

The read-only data storage medium is supposed to be manufactured asalready described with reference to FIG. 4 and the description thereofwill be omitted herein. On the read-only data storage medium 14, themodulated property data 15, which was modulated by the modulation methodA, was recorded.

During the read operation, the type recognizing section 8 senses thestorage medium to read as a read-only data storage medium, therebyturning the switch 13 ON. Also, since the storage medium to read is aread-only data storage medium, the demodulation method A is selected inaccordance with the result obtained by the type recognizing section 8.As a result, the modulated property data 15 is demodulatedappropriately.

Next, it will be described what if one tries to read the recordable datastorage medium 1 on which the encrypted data 2 and the recordedencryption data 12 were illegally copied as they are from the read-onlydata storage medium 14. In that case, the type recognizing section 8senses that the storage medium to read is not a read-only data storagemedium. Accordingly, the switch 13 is turned OFF and the recordedencryption data 12 is not supplied to the decrypting section 10. As aresult, the encrypted data 2 cannot be decoded.

Next, it will be described how to read the recordable data storagemedium, on which user data was written legally, with the read drive. Inthat case, the type recognizing section 8 senses that the storage mediumto read is not a read-only data storage medium. Accordingly, the switch13 is turned OFF and the recorded encryption data 12 is not supplied tothe decrypting section 10. However, since the storage medium to read isa recordable data storage medium, the demodulation method B is selectedin accordance with the result obtained by the type recognizing section8. As a result, the modulated property data 15 is demodulatedappropriately. Then, the decrypting section 10 can decode the encrypteddata 2 by using the modulated property data 15.

Next, the flow of signals during a read operation being performed on aDVD-R, which is used as a specific exemplary recordable data storagemedium, will be described with reference to FIG. 9. On the DVD-R disc101 shown in FIG. 9, property data 105, which had been modulated by themodulation method B, was recorded.

In reading data from the DVD-R disc 101, the flag information 103, whichwas recorded on the user data area 102 of the disc 101, is read out byreading means 106 and the wobbling of the disc 101 is detected. Theoutput of the reading means 106 is demodulated by an eight-to-sixteendemodulating section 107 and then subjected to error correctionprocessing by an error correcting section 108. Thereafter, the flaginformation 106 is sent to a system control section 200. When thepresence of wobbling on the disc 102 is detected by a wobbling detector109, a polarity switching section 110 performs a “polarity switching”operation.

By reference to the flag information 103, the system control section 200recognizes the disc 101 as a DVD-R and instructs the reading means 106to read the property data 105. In response, the reading means 106 movesfrom the user data area 102 toward an inner area of the disc 101 to readthe property data 105. The property data that has been read out in thismanner goes through the polarity switching section 110, RZ demodulatingsection 111 and error correcting section 112 so as to be demodulated andsupplied as a cryptographic key to decrypting section 210. The errorcorrecting sections 112 and 107 may be implemented by the same circuit.

When the system control section 200 instructs writing user data, theuser data (or recording data) is encrypted by an encrypting section 120with the cryptographic key. An error correction code is added by anerror correction code adding section 121 to the encrypted user data,which is then modulated by an eight-to-sixteen modulating section 1200.Thereafter, the user data is written by writing means 123 on the userdata area of the disc 101.

The reading means 106 is implementable as an optical pickup includingthe writing means 123. The tracking control over the optical pickup maybe turned ON in reading the user data but may be turned OFF in readingthe property data from the BCA area.

Hereinafter, it will be described with reference to FIG. 10 how to readthe encrypted user data from the DVD-R.

First, the flag information 103 that was recorded on the user data area102 of the disc 101 is read out by the reading means 106 while wobblingis detected by the wobbling detector 109. The output of the readingmeans 106 is processed by the eight-to-sixteen modulating section 107and the error correcting section 108 and then supplied to the systemcontrol section 210.

When the presence of wobbling on the disc 101 is detected by thewobbling detector, the polarity switching section 110 performs the“polarity switching” operation.

On detecting, by reference to the flag information 103, that the userdata was encrypted with the property data, the system control section200 instructs the reading means 106 to read out the property data 105.The property data 105 that has been read out by the reading means 106 isprocessed by the polarity switching section 110, RZ demodulating section111 and error correcting section 112 so as to be reproduced. Then, thereproduced property data is demodulated by a cryptographic keydemodulating section, thereby reading out the cryptographic key. Then,the cryptographic key is supplied to the decrypting section 210.

When the system control section 210 instructs reading the user data, theuser data is processed by the eight-to-sixteen demodulating section 107,error correcting section 108 and decrypting section 210 so as to be readout. The cryptographic key that has been demodulated from the propertydata is used for decryption.

If the encrypted data (i.e., user data) that had been recorded on aDVD-ROM disc 101 was illegally copied onto the DVD-R, the property datathat was used to encrypt the user data does not match the property datathat was recorded on the DVD-R disc during the manufacturing processthereof. Accordingly, the encrypted data that has been copied onto theuser data area 102 cannot be decrypted by reference to the property datathat has been read out from the DVD-R disc 101. Suppose the propertydata of the DVD-ROM could be written on the property data recording areaof the DVD-R disc by some way or other. Even so, since the property dataof the DVD-ROM disc and that of the DVD-R disc were modulated bymutually different methods, the property data that has been demodulatedby the RZ demodulating section 111 is regarded as an error by the errorcorrecting section 112. As a result, the cryptographic key demodulatingsection fails to demodulate the cryptographic key on the DVD-ROM disc101. Consequently, the encrypted data cannot be decrypted or decoded.

Even if a CSS key has been copied from a DVD-ROM disc onto a DVD-R disc,the read drive does not decode the CSS key on sensing the given storagemedium as a DVD-R through wobbling detection.

Every read drive that can read the recordable data storage medium of thepresent invention has the type recognizing section 8. Accordingly, theswitch 13 may be controlled with just a slight increase in cost.

Also, since the conventional read drive includes a circuit that carriesout the demodulation method A, the function of selectively carrying outthe demodulation method A or the demodulation method B is realizableonly by adding an inverter and a selector to the circuit. In thismanner, the copyright protection can be consolidated with just a slightincrease in cost.

It should be noted that the type recognizing section 8 may distinguishthe recordable data storage medium from the read-only data storagemedium by any method other than the method of detecting the groovewobbling as shown in FIG. 5( c). For example, a method of detecting pitsfrom the lands between the grooves may also be used.

As described above, according to the present invention, a data formatfor use to read or write property data from/on a read-only data storagemedium is different at least partially from a data format for use toread or write property data from/on a recordable data storage medium. Inthe preferred embodiments described above, these data formats aredistinguished from each other by applying mutually different datamodulating methods thereto. However, the present invention is notlimited to these specific preferred embodiments. For example, the errorcorrection data format for the property data may be different betweenthe read-only and recordable ones. In that case, the generatorpolynomial of the error correction data format may be changed.

Alternatively, the information specifying the type of the particulardata format, which was actually selected from multiple types of dataformats for the property data and used to record the property data, maybe written on a track (user data area) of the recordable data storagemedium.

INDUSTRIAL APPLICABILITY

If user data written on a recordable data storage medium according tothe present invention was encrypted with its property data, then a readdrive with no ability to distinguish the recordable data storage mediumfrom a read-only data storage medium cannot decode the user data. Then,a greater number of read drives should be equipped with the function ofrecognizing the type of a given data storage medium and the copyrightprotection can be consolidated.

A read drive according to the present invention cannot read illegallycopied encrypted data from a recordable data storage medium but can readlegally copied encrypted data from the recordable data storage medium.Thus, as for legally copied materials, the present invention is notunbeneficial for the users at all.

1. A recordable data storage medium, including an area on which propertydata, unique to the recordable data storage medium, was recorded and onwhich user data to be used by a user is written after having beenencrypted with the property data, wherein the user data is written onthe area in the same format as a first data format for a DVD read-onlydata storage medium, on which user data to be used by the user waswritten in the first data format and on which property data, unique tothe read-only data storage medium, was recorded in a second data format,wherein at least portion of the property data was recorded on therecordable data storage medium in a third data format that is differentfrom the second data format, and wherein the third data format uses adifferent modulation method from that of the second data format andsatisfies an inverted polarity relationship with respect to themodulation method of the second data format.
 2. The recordable datastorage medium of claim 1, wherein the at least portion of the propertydata that was recorded in the third data format includes cryptographickey information for use to encrypt the user data.
 3. The recordable datastorage medium of claim 1, wherein the modulation method for the seconddata format is a method of converting data “0” into channel data “10”and data “1” into channel data “01”, respectively, and wherein themodulation method for the third data format is a method of convertingdata “0” into channel data “01” and data “1” into channel data “10”,respectively.
 4. The recordable data storage medium of claim 1, whereinthe third data format uses a different error correction data format fromthat of the second data format.
 5. The recordable data storage medium ofclaim 4, wherein the error correction data format of the third dataformat uses a different generator polynomial from that of the errorcorrection data format of the second data format.
 6. The recordable datastorage medium of one of claim 1, wherein at least portion of theproperty data was recorded on a burst cutting area (BCA).